Organic light emitting devices (OLEDs) emit light in response to an electric current. The OLEDs usually include layers of semiconductor materials for carrying out this functionality. On application of a voltage across the layers of the semiconductor materials, electrons and holes are injected from electrodes placed on either side of the layers of the semiconductor materials. The electrons and holes recombine in the layers of the semiconductor materials and form excitons, thereby emitting light.
The OLEDs are increasingly becoming a popular technology for various applications including flat panel displays and lighting systems for illumination. The OLEDs are usually manufactured in large sizes using large substrate, i.e., manufacturing large substrate area products. The OLEDs are manufactured by employing various methods such as panel by panel, roll to roll and other such large form factor manufacturing processes.
Further, such large form factor manufacturing processes tend to increase defects and non-uniformities in various layers of the OLEDs because commonly used methods of layer deposition such as screen printing, dip coating, spray coating, doctored blade, spin coating, sputtering, evaporation etc are not suitable for large areas. For example spin coating when done on large substrate, gives variation in height of deposited layers from an inner periphery to an outer periphery. These defects lead to poor device performance and very low process yields for the OLEDs. Also, in manufacturing of large substrate area OLEDs, there are defects such as pinholes, inhomogeneity etc. in the layers deposited on the large substrate area OLEDs.
The large substrate area OLEDs have to be sliced to form organic light emitting devices of required product sizes, thereby causing area and material losses and increasing costs. Also, this process of slicing requires additional time thereby reducing yield. For example, for applications such as mobile phone displays, the large substrate area OLEDs will have to sliced into smaller sizes leading to a reduction in yield.
Furthermore, many of these manufacturing processes are not scalable leading to delays in faster commercialization for these devices. Therefore, the large substrate area OLEDs or smaller OLEDs manufactured by cutting the large substrate area OLEDs are poor in quality, inefficient and costly.
In light of the above, there is a need of a method of manufacturing OLEDs which overcomes one or more of the above mentioned problems and creates a process that can mass manufacture high quality OLEDs with high yield, using substrates having a small area.